To compare the efficacy of crizotinib, pemetrexed and other chemotherapy regimens as a first-line treatment in patients with anaplastic lymphoma kinase (ALK)-positive non-small cell lung cancer (NSCLC) in real world clinical use and to evaluate the +86–571-87,236,876 predictive clinical factors of the efficacy of crizotinib. The gene discussed is ALK; the disease is non-small cell lung carcinoma.